Loop taker mechanism for chainstitch sewing machines



Sept. 5, 1961 K. POLLMEIER 2,998,737

LOOP TAKEJR MECHANISM FOR CHAIN-STITCH SEWING MACHINES Filed June 22, 1959 3 Sheets-Sheet 1 i 36 26 27 31 12 Fig 2 INVENTOR 5 25 33 KONKA) POLLHEIEL B QIIYW Sept 1961 K. POLLMEIER 2,998,787

LOOP TAKER MECHANISM FOR CHAIN-STITCH SEWING MACHINES Filed June 22, 1959 3 Sheets-Sheet 2 INVENTOR KONRAD PoLLMc-oc- 2) rm ,4 Tr S.

K. POLLMEIER Sept 5, 1961 LOOP TAKER MECHANISM FOR CHAIN-STITCH SEWING MACHINES Filed June 22, 1959 3 Sheets-Sheet 3 Fig. 6

INVENTOR Kw Rm 7 LME/flE Unite corporation of Germany Filed June 22, 1959, Ser. No. 821579 10 Claims. (Cl. 112--,20tl) This invention relates to a loop taker mechanism for chain-stitch sewing machines of the kind in which both the main swinging movement and the lateral shift movement of the loop taker are derived from an oblique crank.

Loop taker drives of the kind are known in which the loop taker carrier has a shaft of a journal which is arranged at right angles to the loop taker driving shaft, and in which the oblique crank is embraced by a sleeve which has a swinging bar whose axis lies perpendicularly to the crank and runs perpendicularly to the said carrier shaft.

In a known loop taker drive of this construction a downwardly-projecting cylindrical journal is firmly fixed on the said sleeve driven by the shaft. of the oblique crank, the axis of which shaft runs perpendicularly to the axis of the sleeve and the crank lies obliquely thereto. The journal is guided in a cylindrical bore in a lubricated carrier support with which the loop taker carrier journal is rigidly connected and which runs perpendicularly to the axis of the sleeve journal.

This known loop taker drive can very easily become fouled as its moving elements lie freely under the stitch plate. In addition there is the danger that the parts in bricated by hand may receive either too little or too much lubricant with, in one case a premature wearing of the driving parts concerned and, in the other case, a dirtying of the material being sewn. It is also disadvantageous that only one sleeve journal for the transmission of movement is provided on the loop taker carrier, whereby the journal and the loop taker carrier sleeve sliding on it must be comparatively longif a satisfactory guidance is to be obtained. The consequence of this is that besides a large constructional height of the lubricator drive there is also a. noisy running of the sewing machine at higher sewing speeds, owing to the unbalanced masses. In addition, the building assembly and removal of the loop-taker driving parts, as with all other hitherto known loop taker drives, is complicated and time consuming, as almost all the shafts and driving shafts have their bearing points below the material carrier plate in the casing.

The present invention has as its object to provide a loop-taker driving parts, as with all other hitherto known said kind which permits of a very high sewing speed and a satisfactory and almost attendance free lubrication which obviates the danger of soiling of the parts; which is small in dimensions; is easily accessible; in which the parts are exchangeable quickly and without trouble, and which permits of the adjustment for the variation of the elliptical loop-taker path Within certain limits.

According to the claimed invention the preventproblems are avoided by reason of the fact that the oblique crank which is fixed in the driving shaft projects into a separate casing in which the link carrying the thread looptaker, moved by the oblique crank, is mounted. By this construction the drive, consisting of the driving shaft with the oblique crank and the swinging bearing, the link with the loop-taker and the casing, represents a closed constructional unit which is exchangeably arranged on the base plate of the sewing machine. The casing containing the loop taker drive itself is closed oil tight for the purpose of sealing a supply of lubricant and means is provided whereby the oil level is capable of being checked through an inspection glass.

For the fixing of'the casing to the base plate there is provided a bearing bush, which receives the end of the driving shaft which extends into the casing. An end of this bush is arranged in an opening of a bearing forming a part of the base plate and is provided with clamping means for-the purpose of adjusting the loop taker in a radial, as well as an'axial direction in relation to the needle, andhis capable of being firmly clamped. For the purposeof varying, the elliptic movement path the bush is arranged to be movable in an axial direction in the casing and is capable of being clamped.

In a preferred embodiment of the invention the loop taker carrying shaft has a link surrounding the sleeve with two bearing places for receiving bearing journals formed with the sleeve. In this embodiment of the loop taker drive, further bearings are inserted between the oblique crank and the sleeve.

In another embodiment, the sleeve mounted on the oblique crank has a cylindrical sliding surface. provided with lubricant pockets and is slidably mounted and guided in a cylindrical link formed with the loop taker carrier shaft and provided with passage openings 'for the oblique crank journal.

Two representative embodiments of the invention are illustrated in the accompanying drawings by way of ex ample in which:

FIG. 1 is a front elevation of one example of the loop taker drive and showing its attachment to the material carrier plate of a sewing machine;

FIG. 2 is a sectional inverted plan of the loop taker drive on the line II-II of FIG. 1; 1

FIG. 3 is a vertical section of the same on the line Illiii of FIG. 2;

FIG. 4 is a part plan View of the loop taker drive, with the elliptical path of movement of the loop taker shown in broken lines; and

FIG. 5 is a vertical section on-the line V-V of FIG. 1, to show the fixing of the bearing bush in the casing;

FIG. 6 is a sectional inverted plan similar to FIG. 2 but of another embodiment of the loop taker drive;

FIG. 7 is a vertical section similar to FIG. 3 of the em bodiment shown in FIG. 6; and

FIG. 8 is anexploded view of the individual'parts of the drive illustrated in FIGS. 6 and 7.

In the first embodiment, as can be seen in FIGS. 1 and 2 the moving parts of the loop taker drive are located A hearing block 7 (FIGS. 1 and 2) which is connected to the material carrying plate 8, has a bore 9 for receiving the projecting end of the bearing bush 2 and has also a slot 19 for the clamping of the bearing bush 2 with the aid of clamping screws 11, thereby mounting the casing 1 in the said bearing block 7.

On the end of the driving shaft 3 an oblique crank 12 (FIGS. 2 and 3) is fixed 'by means of a screw 13. Such oblique crank 12 is embraced by a sleeve 14, and to avoid friction between the oblique crank 12 and the sleeve 14 two needle roller bearings 15, 16 are inserted between those parts. The sleeve 14 is constructed with two radially extending cylindrical bearing journals or trunnions 1.7, 118, projecting upwards and downwards (in FIG. 3) the axes-of these'journals being perpendicular to'the common axis of the sleeve 14 and of the oblique crank 12; The sleeve 14 is surrounded by an open link 19. which has two opposite, aligned bores serving as bearings for the respective journals 17, 18 of the sleeve.

The open link or cage 19 is constructed with a short bearing journal 20 at one side and a long bearing journal 22 at the other side, this last projecting from the casing 1 and supporting the loop-taker carrier arm 21 the rotation axis of which runs perpendicularly through the axis of the driving shaft 3. The bearing journal 20 is mounted for rotary and axial movement in a bush 23 which is inserted in the casing 1, and it is prevented from moving away by means of a screw 24 (FIG. 2). The bearing journal 22 is mounted in a bush 25 which is inserted into an end cover 27 of the casing 1, sealed by means of a packing ring 26 against the casing 1. The bearing point in the casing 1 for the journal 20 is sealed against the escape of the lubricant by means of a pot-like cover or hollow cap 28, with the insertion of a packing ring 29 between this and the casing 1, and with the aid of a screw 30 (FIG. 3). A packing 31 inserted in the end cover 27 for the bearing journal 22, is retained by means of a plate 33 which is fixed on the cover 27 by means of screws 32.

An inspection glass 35 inserted in the casing 1 and sealed with a packing ring 34 serves for checking the level of the lubricant in the casing 1. The filling of the lubricant may take place, after swinging up the upper part of the sewing machine, through an opening which, in the operating position, is closed by means of the screw 36. An oil drainage screw 37 inserted in the floor of the casing 1 serves for the emptying of the casing. In order to prevent the leakage of the oil from the casing, there is located between the bearing bush 2 and the casing 1, a further packing 38.

As can be seen in FIG. 4, the thread loop taker 39 describes the elliptical path indicated in the broken line at 40 when the driving shaft 3 is rotated. The magnitude of the axial movement of the loop taker 39 (minor axis of the ellipse 40) is determined by the degree of inclination of the oblique crank 12, while the lateral swinging movement (major axis of ellipse 4-0) perpendicularly to the said longitudinal movement is determined by the degree of eccentricity of the axis of the sleeve 14 in relation to the axis of the driving shaft 3.

The lateral swinging movement of the loop taker 39 may be controlled within certain limits by the displacement of the driving shaft 3 in axial direction. For this purpose, after loosening the clamping screw 6 the hearing bush 2 in the casing 1 and with it the oblique crank 12 with its driving shaft 3 .can be moved thereby, according to the direction of such movement, the engaging point of the journal axis of the sleeve 14 is moved more or less away from the axis of the driving shaft 3.

The lateral adjustment of the loop taker 39 in relation to the needle 40 may take place by a rotation of the casing 1 with the bearing bush 2 in the bearing block 7, after releasing the clamping screws 11.

In the second embodiment of the loop taker drive, as illustrated in FIGS. 6 to 8, a sleeve 41 is placed on the oblique crank 12, and this sleeve has a sliding surface 42 which is interrupted by lubricant pockets 43. The sleeve 41 is slidably mounted and guided in a cylindrical link or bush 44- which has elongated openings 45 for the oblique crank 12 and is constructed with a short bearing journal 47 for mounting in the casing 1, and a long journal 46 for mounting in the end cover 27.

The manner of operation of this embodiment is, in principle, the same as that in the first-described embodiment.

As can be seen from the above description and from the drawings, the enclosed location of the driving parts in the comparatively small casing 1, has the advantage that a rapid exchange of the whole loop taker unit for another is possible. For this purpose it is necessary merely to loosen the clamping screws 11 in the bearing block 7 (FIG. 1) and the connection of the driving shaft 3 with its driving wheel (not illustrated) in order to be able to draw the loop taker unit out of the sewing machine as an enclosed assembly.

What I claim is:

1. In a looper mechanism for sewing machines, the combination with a driving shaft, of a fixed bearing block, an elongate bush having one end portion secured in said bearing block, said driving shaft having an end rotatably supported in and extending through said bush, a fluidtight casing having an end formed with a bore in which an opposite end portion of said bush is fitted, said shaft end terminating within said casing, a journal supported by and extending through a wall of said casing for rotational and axial movement on an axis perpendicular to said driving shaft, said journal having an outer end exteriorly of the housing, a loop taker carrier secured to the said outer end of the said journal, and mechanism within the housing forming an operative coupling between the said end of the driving shaft and said journal which is constructed and arranged to transmit elliptical swinging and lateral swinging movements from the driving shaft to said loop taker carrier.

2. The invention according to claim 1, wherein the casing is rotatable on the said opposite end portion of the bush and the casing and mechanism carried thereby are supported by the bush and the shaft end.

3. In a looper mechanism for sewing machines, the combination with a work material supporting plate, of a bearing block carried by said plate, an elongate casing having a bush receiving bore in one end and extending longitudinally thereof, an elongate bush having one end secured in said bearing block and having its other end ex tending into and secured in said bore, a driving shaft having an end extending through said bush and terminating in the casing, said casing in the bore end thereof being longitudinally split and releasably constricted into holding engagement with and about said bush whereby the casing may be turned for adjustment on the bush, a journal extending through and rotatably supported in a wall of the casing for turning on an axis perpendicular to and intersecting the axis of said drive shaft, a crank arm carried on the said terminal end of the driving shaft and disposed obliquely to the axis of the shaft, a loop taker carrier on the outer end of said journal, and a pivotal coupling within the casing between said crank and the inner end of the journal for transmitting combined rotary and axial movement to the journal from the driving shaft.

4. The invention according to claim 3, with means rendering said casing fluid tight to contain a fluid lubricant.

5. The invention according to claim 4, wherein said casing at the opposite end thereof from the bushing has a window therein for observing lubricant fluid level.

6. The invention according to claim 3, wherein said pivotal coupling comprises a first body having a bearing opening into which said crank extends and is adapted to rotate, a second body, a pivotal coupling between the first and second bodies for relative turning of the same on an axis perpendicular to and intersecting the longitudinal axis of the crank arm, and a rigid connection between the second body and the inner end of said journal through which said combined movements are transmitted.

7. In a looper mechanism for sewing machines, the combination of a fixed bearing block, an elongate bush having an end portion secured to the bearing block, an elongate casing having in one end a longitudinally directed bore, said bush having its other end extending into and secured in said bore, a driving shaft having an end extending through said bush and terminating within the casing, a short straight crank in the casing and secured at one end to said terminal end of the driving shaft and disposed obliquely to the turning axis of the shaft, a first body having a bore in which said crank is rotatably positioned, a second body encircling the first body and crank, said first and second bodies being joined for relative turning on an axis perpendicular to and intersecting the longitudinal axis of the crank, said casing having opposite walls provided with aligned bush openings, first and second bushes in said aligned openings and aligned on an axis perpendicular to and intersecting'the axis of the driving shaft, first and second journals respectively mounted in said first and second bushes, said first and second bodies being positioned between said journals, said second body being secured to the inner ends of said journals, said second journal having an outer end extending beyond the outer side of the casing, and a loop taker carrier secured to said outer end of said second journal.

8. The invention according to claim 7, with means rendering the casing fluid tight for containing a lubricant fluid.

9. The invention according to claim 7, wherein said first body comprises a sleeve carrying oppositely directed radial and aligned trunnions and said second body comprises an open link having said trunnions rotatably coupled to opposite sides thereof, other opposite sides of the open link being secured to the inner ends of said journals.

10. The invention according to claim 7, wherein said first body comprises a solid cylinder having the bore diametrically therethrough and the second body comprises a hollow cylinder having the solid cylinder fitted therein for rotary motion and having opposite concentric arcuate slots for receiving said crank, and the-said inner ends of the journals being secured to opposite sides of the hollow cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 1,107,659 DeVoe Aug. 18, 1914 2,160,355 DeVoe May 30, 1939 2,301,460 Sauer Nov. 10, 1942 

